This invention relates to an oil hydraulic circuit for a gripping device, which can provide a variable clamping force with which to grip an object.
The oil hydraulic circuit for a gripping device used for an operating machine, e.g., a construction machine, has a relief valve. The clamping force is usually changed by changing the preset relief pressure of the relief valve with an adjustment screw. Where the clamping force is frequently changed, however, the operation involved is felt very cumbersome. In addition, sound noise is liable to be produced from the relief valve.